The instant invention relates to mapping and positioning techniques in general and, more particularly, to a self-contained mapping and positioning system especially suited for determining the position of an object located within a region, such as a mining vehicle within a mine tunnel, utilizing point cloud data, i.e., a set of data points representing the topography of the region.
Mine tunnel outline plan views (xe2x80x9cTOPESxe2x80x9d) are required for underground mine planning. Present techniques require teams of skilled surveyors using conventional surveying techniques and equipment to physically traverse the stopes and drifts to obtain the raw data for the topes. The raw data consists of point-to-point measurements. The mapping data collected by the surveyors is imported into a CAD package to produce mine tunnel plan views.
Sending surveying crews into underground excavations can be tedious work. Moreover, the assembling and utilization of highly skilled personnel contributes to the cost of underground mining.
Due to the ceaseless press of cost reduction and heightened safety concerns, there is a continuing desire on the part of hard rock miners to automate mining systems. By automating as many and minimizing cycles as possible, the dangers and expenses caused by the presence of personnel at the actual working zones of the mine may be reduced. By placing the miner or other mine professional in a safe and secure remote location, preferably at the surface, increased safety, cost efficiency and production are encouraged.
In particular, robotic mining techniques require dependable mapping, navigation and positioning systems. For surface mining (as well as other activities), increasing success has been found with the use of global positioning systems utilizing earth satellite navigation.
However, in underground mines and in certain surface structures, the signals from the orbiting satellites cannot reach the targeted equipment. Accordingly, sophisticated dead reckoning systems have been developed. Typical systems utilize sound, electromagnetic means (lasers, visible light, radar) or gyroscopes or combinations thereof to remotely guide and operate mobile underground equipment.
A difficulty with remotely operated equipment is securing an initial reference datum point in X-Y-Z space. Due to the relative complex location algorithms used in navigation systems, the jumping off point must be measured with great accuracy otherwise even small errors will quickly become magnified thereby throwing off the reconnoitering ability of the apparatus. This problem is especially onerous if a toping system is involved. Any deviation may render the resulting map worthless when critical parameters are at stake.
Further, dead reckoning systems, may render false mapping, navigation and positioning readings due to natural phenomenon, such as electrical storms, and the uneven, crater-like surface of the mine or an overhead surface which tend to roll and shake the vehicle carrying laser equipment and/or gyroscopes.
Accordingly, there is a need to produce less labor intensive accurate topes of underground regions, enclosed structures, and overhead surfaces for later use in navigating and positioning an object, such as a mining vehicle within a mine tunnel.
A need also exists in developing a self-contained mapping and positioning system which does not use global positioning and dead reckoning systems in positioning an object and determining the position of the object within a region after an initial reference position of the object is known.
There is provided a self-contained mapping and positioning system that is capable of mapping the topography of a region, such as a mine tunnel, and further being able to use the mapped data to determine the position of an object, such as a mining vehicle within the mine tunnel. The system includes an inertial navigation system, a central processing unit, a three-dimensional database, a three-dimensional camera system, an operator console and a survey system having a three-dimensional laser scanner.
The survey system which is capable of an accuracy of xc2xd mm over 12 m is attached to a vehicle that is remotely operated through the region. The survey system using the three-dimensional laser scanner produces point cloud data, i.e., a set of data points representing the topography of the region, as well as raster imagery. The point cloud data is stored within a storage device until the entire region is mapped and then is transmitted to the operator console to be post processed. The post processing involves the consolidation and verification of the data collected in the field and setting the data in the requested coordinates. The final step is the exporting of the information to the three-dimensional database and the indexing of the data for ease of use by the central processing unit.
To determine the position of the object within the region, the system of the instant invention initializes the mining vehicle in its current position or initial reference point (xe2x80x9cIRPxe2x80x9d), as described in co-pending U.S. patent application Ser. No. 09/515,299 titled xe2x80x9cAutomated Guided Apparatus Suitable for Toping Applicationsxe2x80x9d filed on Feb. 29, 2000 and having a common assignee; the contents of which are incorporated herein by reference. The IRP is fixed with respect to the point cloud data stored within the database. The object is then either remotely or directly guided from the IRP to another position where it is brought to an estimated position by the inertial navigation system or is remotely controlled for performing work, e.g., drilling a mine heading.
After a predetermined time of moving the object, there is an error in the position of the object and the operator console makes a call to the central processing unit on board the object to automatically calculate the true position based on the point cloud data stored within the database to update the position of the object. This is done by approximating a search range for the database according to the estimated position. A subset of data corresponding to the search range is removed from the database. The three-dimensional camera system then scans images of the surface in proximity to the object and converts the images to a patch of point cloud data. The patch of point cloud data is then matched using a matching algorithm against the subset of data corresponding to the search range of point cloud data removed from the three-dimensional database until there is less than a predetermined minimum error distance, preferably, in the range of 2-4 cm. At that point, the true position of the object is known. This new position is then put back into the inertial navigation system and the positional data of the object is updated with the correct positional data.
The invention is especially useful for guiding a mining vehicle within a mine tunnel from an initial reference point, determining the position of the mining vehicle with respect to the initial reference point, and updating the positional data associated with the mining vehicle. It also may be used for guiding, determining the position, and updating the positional data of other objects, such as overhead surface vehicles.